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Subject: Re: [PATCH 0/4] Was: deferring __fput()
From: Mimi Zohar <zohar@linux.vnet.ibm.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        ". James Morris" <jmorris@namei.org>,
        linux-security-module@vger.kernel.org,
        linux-kernel <linux-kernel@vger.kernel.org>,
        David Howells <dhowells@redhat.com>
Date: Sun, 01 Jul 2012 21:46:31 -0400
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On Sun, 2012-07-01 at 21:57 +0100, Al Viro wrote:
> On Sun, Jul 01, 2012 at 03:50:02PM -0400, Mimi Zohar wrote:
> > Replacing it with a call to __fput(), the system boots.
> 
> "it" being just the part under that if (unlikely(...)))?  Very interesting...  If so, we
> have some kernel thread ending up with delayed __fput() which somehow makes dracut (assuimg
> you are using fedora initramfs to go with fedora config) unhappy.  With your own patch,
> doing async __fput() in a lot of cases when this one doesn't delay past the return to
> userland managing to survive the boot...  I wonder which files end up triggering that fun
> and which kernel thread is responsible...  Could you slap a printk() in there, showing
> file->f_dentry->d_inode->i_mode (octal) and at least file->f_dentry->d_name.name?
> Along with the current->comm[], all under that inner if ().  And see which ones end up
> going that way by the time execve() of /sbin/init fails.

pid=1 uid=0 d_name=init comm=swapper/0 dev="rootfs" mode=100775
pid=1 uid=0 d_name=bash comm=swapper/0 dev="rootfs" mode=100755

> It would be nice to see which sys_mount() calls are made and which (if any) fail, BTW.
> I wonder if it even gets to mounting the right root...